FIELD OF THE INVENTION
The present invention is in the field of image intensifier tubes of the type used for night vision devices. More particularly, the present invention relates to an image intensifier tube of the type which employs electrostatic electron-optics to invert and focus an image created by the tube. Still more particularly, the present invention relates to such an electrostatically-focused image intensifier tube having means for virtually eliminating the long-standing problem of "PC Flash". In the use of such a night vision device with an image intensifier tube, the user sees an intensified image of a scene which is illuminated only by low-level light, and which is too dim to be viewed with the natural vision (such as a night-time scene, or a scene inside of a darkened structure with only a little natural or artificial illumination). However, the user may also see bright spots at the periphery of the image which may come and go rapidly or which may persist for some considerable time. This problem is known generally as "PC Flash", or photocathode flash, and results in the user seeing bright spots, which do not originate with the scene being viewed, but which originate within the image intensifier tube itself. The bright spots obscure a portion of the image which should be provided by the night vision device, and interfere with the correct interpretation of the image presented. Also, the bright spots may suggest to the user of the night vision device that objects are present which in fact do not exist. The present invention provides an electrostatically-focused image intensifier tube, and method of making such a tube, which is virtually without the problem of PC flash.